Semiconductor integrated, electronic control circuit incorporating an electrically programmable, electronic non-volatile memory device

ABSTRACT

An integrated electronic control circuit comprises a microcontroller connected to at least one volatile memory, at least one input/output port, a plurality of control devices, and an electronic non-volatile memory device comprising a non-volatile memory cell matrix linked to a control register, and a switch element connected between a voltage reference and the cell matrix to enable the program mode of the cell matrix under control by the microcontroller.

TECHNICAL FIELD

This invention relates to a semiconductor integrated, electronic controlcircuit incorporating an electrically programmable, electronicnon-volatile memory device.

The invention is, particularly but not exclusively, directed to aprogrammable type of integrated electronic control circuit includingintegrated analog devices, along with digital devices operative tocontrol the analog devices. The circuit is, particularly but notexclusively, intended for controlling electromechanical devices, and thedescription that follows will cover this field of application forsimplicity of illustration.

BACKGROUND OF THE INVENTION

As is well known, in the specific field of this invention, SSP (SuperSmart Power) power devices are currently employed which have analog,power and signal components, as well as digital control components forcontrolling the power components, both integrated on the samesemiconductor die.

The control action is generally provided and managed by amicrocontroller which runs a control program stored in a memory, alsoprovided on the same die.

In particular, memories of the ROM type or the OTP EPROM (One TimeProgrammable EPROM) type are integrated for that purpose.

This approach has certain drawbacks in applications where calibrationparameters are to be introduced in order to exert an adequate controlaction on each specimen of the device to be controlled.

The above requirement is currently met by having these parameters storedin memories other than those storing the control program. These memoriesare of the non-volatile type, such as EEPROMs, and are also integratedon the same die as the microcontroller. However, due to the high arearequirements of the basic cell, non-volatile memories must bedimensioned to occupy the least possible amount of circuit area.

This prior approach affects the versatility of the control program inthat only a limited number of parameters of the device to be controlledcan be stored.

Another possible solution would be that of storing such calibrationparameters into memories outside the die.

While achieving its objective, not even this solution would be devoid ofdrawbacks. In fact, it is important for certain applications that thenumber of pins taken up by the connections to external circuitry be keptas small as possible. Furthermore, the use of external memories adds tothe complexity of the control action for managing the external memories.

SUMMARY OF THE INVENTION

An embodiment of this invention provides an electronic control circuitwhich can be readily programmed according to the external devices to becontrolled. The circuit has such constructional and functional featuresas to allow the calibration parameters to be also stored after theinitial programming, thereby to overcome the limitations and/ordrawbacks with which prior art devices are still beset.

The control circuit is a semiconductor integrated, electronic controlcircuit which comprises a microcontroller and a non-volatile memorydevice having a matrix of non-volatile memory cells, and a switchelement for causing the matrix of memory cells to enter the program modeunder control by the microcontroller.

The microcontroller is connected to at least one volatile memory, atleast one input/output port, a plurality of control devices, and anelectronic non-volatile memory device comprising a matrix ofnon-volatile memory cells linked to a control register. The electroniccontrol circuit comprises a switch element connected between a voltagereference and said cell matrix to enable the program mode of the cellmatrix under control by the microcontroller.

Advantageously, the switch element is driven by the control registerconnected to the matrix.

Advantageously, the switch element is a p-channel MOS transistor.

The features and advantages of a circuit according to the invention willbe apparent from the following description of an embodiment thereof,given by way of non-limitative example with reference to theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of an electronic control circuit according tothe invention.

FIG. 2 shows an electronic memory device as integrated to the circuit ofthis invention.

DETAILED DESCRIPTION

Shown in FIG. 1 is a block diagram of an electronic control circuit 8according to an embodiment of this invention. The control circuit 8comprises a microcontroller 9, such as a compatible Motorola HC05microcontroller, which is connected to an electronic memory device 10through data lines D BUS, address lines ADDR BUS, and control linesCNTRL BUS.

In FIG. 2, individual components of the electronic memory device 10 areshown. This device 10 comprises a matrix 1 of memory cells, e.g., a 4kbyte EPROM cell matrix. This EPROM matrix 1 is controlled by a controlregister 2 and connected to the lines D BUS, ADDR BUS, and CNTRL BUS.

Advantageously, a switch element 3 is provided which has a firstterminal 4 connected to a voltage reference Vs, a second terminal 5connected to the control register 2 of the EPROM, and a third terminal 6connected to the terminal for the program voltage Vpp of the EPROM 1.

In particular, the switch element 3 can be a MOS transistor.Advantageously, the MOS transistor is a p-channel transistor becausethis type of transistor can be readily integrated to operate on theprogram voltage Vpp of the EPROM 1, and has a relatively small intrinsicoperational resistance R_(DSon), which allows more accurate provisionsto be made for reliability after integrating the memory device 10 on thedie.

The MOS transistor may be a high voltage transistor, for example.

Connected to the microcontroller 9 are a conventional oscillator 11,necessary to the operation of the microcontroller 9, and a conventionalreset unit 12.

Shown at 16 is the power section of the control circuit 10, whichsection is controlled from a logic block 17 and an over voltage-overtemperature block 18.

The logic block 17 is driven by a constant frequency, variable dutycycle modulator 19 which is also connected to the microcontrollerthrough the lines D BUS, ADDR BUS and CNTRL BUS.

Further connected to the microcontroller 9 are a counter 20 functioningto reset the circuit 8, a RAM 21 having, for example, a 256 bytecapacity, a further timer 22, an interface 23 for managing the outwardconnections, and an analog-to-digital converter 25 having a multiplexer26 connected thereto to pick up different signals from the circuitoutside for setting the control circuit 8.

The input of the multiplexer 26 can also be applied a signal (V_(s) /7)proportional to the supply voltage Vs. The indication from this signalis processed through the control program to prevent supply voltagespikes from destroying the EPROM 1.

The control circuit 8 is additionally provided with a first regulator 13for supplying a low voltage to the digital section of the controlcircuit, and a second regulator 14 connected to a charge pump 15 fordriving, at a higher voltage than said low voltage, the analog powersection of the control circuit.

The manner of entering the calibration data of the control program ofthe control circuit 8 to the EPROM cell matrix 1 will now be described.

The control program can be loaded into the EPROM 1 before actuallyinstalling the control circuit 8 in the user's apparatus, for example.

Once the control circuit 8 is installed, in order to store calibrationdata into the EPROM matrix 1, a supply voltage Vs, equal to the programvoltage Vpp of the memory cell matrix 1, is applied.

Before applying the supply voltage Vs to stored the calibration data inthe EPROM cell matrix 1, a portion of the control program is transferredinto the RAM 21. This operation is made necessary because the EPROM cellmatrix 1 cannot be read from and written in simultaneously.

Thereafter, the switch 3 is operated by a control signal from theregister 2, and the EPROM cell matrix 1 caused to enter the write orprogram mode.

Upon entering the program mode, the calibration parameters are storedinto the EPROM cell matrix 1. The switch 3 then is turned off and thememory cell matrix 1 is caused to exit the program mode.

In summary, the electronic control circuit of this invention allows thecontrol action of each device to be calibrated by having an electronicmemory device, provided with a switch to control the store phase of thememory device, jointly integrated with a microcontroller.

From the foregoing it will be appreciated that, although specificembodiments of the invention have been described herein for purposes ofillustration, various modifications may be made without deviating fromthe spirit and scope of the invention. Accordingly, the invention is notlimited except as by the appended claims.

What is claimed is:
 1. An integrated electronic control circuit,comprising:a non-volatile memory having a data input, an address input,and a program enable input; a control register having a data output, anaddress output, and a program enable output, the data and addressoutputs being coupled to the data and address inputs, respectively; anda control switch having a control terminal coupled to the program enableoutput, a first conduction terminal coupled to a voltage reference, anda second conduction terminal coupled to the program enable input of thenon-volatile memory, the control switch being structured to electricallyconnect the voltage reference to the program enable input in response toreceiving a program enable signal from the control register and therebycause data from the data output of the control register to be stored inthe non-volatile memory at an addressed indicated by the address outputof the control register.
 2. The electronic control circuit of claim 1,further comprising a microcontroller having data, address, and controloutputs coupled to data, address, and control inputs, respectively, ofthe control register, the control register producing the program enablesignal in response to receiving a control signal from themicrocontroller.
 3. The electronic control circuit of claim 1 whereinthe non-volatile memory includes an EPROM.
 4. The electronic controlcircuit of claim 1 wherein the control switch includes a p-channel MOStransistor.
 5. The electronic control circuit of claim 1, furthercomprising a volatile memory coupled to the non-volatile memory, thecontrol register being disabled from writing to the non-volatile memorywhile program data is being transferred from the non-volatile memory tothe volatile memory.
 6. A control method, comprising:storing a controlprogram in a non-volatile memory; storing calibration data in a controlregister; transferring the calibration data from the control register tothe non-volatile memory in response to receiving a program enable signalat a program input of the non-volatile memory; and switching the programinput of the non-volatile memory into electrical connection with avoltage reference in response to a control signal, the voltage referenceproviding the program enable signal to the program input of thenon-volatile memory.
 7. The control method of claim 6, furthercomprising transferring at least a portion of the control program fromthe non-volatile memory to a volatile memory before storing thecalibration data in the non-volatile memory.
 8. The control method ofclaim 6 wherein the switching act includes providing a control signal toa control terminal of a switch from a control register.
 9. The controlmethod of claim 8 wherein the switch act further includes using amicrocontroller to cause the control register to provide the controlsignal to the switch.